The development of integrated circuitry, particularly RFIDs, has permitted use of such devices in a wide range of applications. RFIDs first appeared in tracking and access applications during the 1980s. These wireless systems allow for non-contact reading and are effective in manufacturing and other hostile environments where bar code labels could not survive. RFID has established itself in a wide range of markets including livestock identification and automated sorting systems because of its ability to track moving objects. They can be operated passively or actively. While both use radio frequency energy to communicate between a tag and a reader, the method of powering the tags is different. Active RFIDs use an internal power source (battery) within an RFID tag to continuously power the RFID, whereas passive RFIDs rely on energy transferred from the reader to the RFID tag to power the RFID.
Recently, RFIDs have been used in a product packaging such as containers and closures. The utilization of an RFID with a closure and container combination has a wide variety of applications, including identification of contents, product promotions, storage and dissemination of product information including product processing, quality assurance, including tamper-indication. However, a problem existing with many applications of RFIDs in closures is that the RFID can be damaged during the production of a closure having an RFID or when sealing the closure having the RFID to a container. Other problems have been found with the performance of the RFID when metals are incorporated into a closure or closure and container combination.
Induction sealing is a process often employed in assembling a closure or in sealing a closure to a container neck. Often times a film or sealing disc is used to seal in a container contents. This has been accomplished by putting an induction foil adjacent an inner surface of a top wall of a closure and a sealing disc adjacent the lower side of the induction foil. The induction foil is typically comprised of a nonferrous metal such as copper, steel, gold, and aluminum. A magnetic field is established by a radio frequency coil about the closure which induces a current in the metal induction foil. As the current flows through the metal induction foil, the resistivity of the induction foil generates heat which partially melts the thermoplastic materials which are adjacent thereto, typically a portion or component part of the closure, container, or both resulting in chemical bonding of the adjacent thermoplastics.
Problems have been encountered with use of RFIDs with containers and closures having induction foil incorporated therein. The heat generated during the induction process can render an RFID device inoperable thus restricting or even prohibiting the use of an RFID device when using an induction sealing process with a closure or closure and container combination. Additionally, radio waves bounce off metal causing interference from the metal disrupting the RFID signal. Moreover, metal causes eddy currents in the vicinity of the RFID reader antennae which absorb RF energy, thus reducing the overall effectiveness of the RFID field. These eddy currents also create their own magnetic field perpendicular to the metal surface which can cancel the reader field. Furthermore, metal can also detune both reader and tag antenna, causing added parasitic capacitance reducing system performance. Finally, at some frequencies the energy reflected by metal creates interference between the tag and reader. Therefore, having an RFID in a metal environment can cause reductions in actual read and write rates, ranges and reliabilities.